Three-dimensional data encoding method, three-dimensional data decoding method, three-dimensional data encoding device, and three-dimensional data decoding device

Abstract

A three-dimensional data encoding method includes: calculating coefficient values from items of attribute information of three-dimensional points; quantizing the coefficient values to generate quantization values; and generating a bitstream including the quantization values. One or more items of attribute information are classified, for each of three-dimensional spaces, into one of groups, the three-dimensional spaces (i) being included in a plurality of three-dimensional spaces, and (ii) including, among the three-dimensional points, three-dimensional points including the one or more items of attribute information. In the quantizing, the coefficient values are quantized using a predetermined quantization parameter or one or more quantization parameters for one or more groups, the one or more groups being included in the groups and including one or more items of attribute information used to calculate the coefficient values, the one or more items of attribute information being included in the items of attribute information.

What is claimed is: 
     
         1 . An encoding method to be executed by an encoding device that includes a processor and a memory, the encoding method comprising:
 calculating coefficient values from items of attribute information, each of the items of attribute information corresponding to a different one of a plurality of points;   generating quantization values from the coefficient values using a first parameter, using, for a coefficient value corresponding to a point located in a predetermined region among the plurality of points, a value assigned as the first parameter to the predetermined region, and using, for a coefficient value corresponding to a point not located in the predetermined region among the plurality of points, a predetermined value as the first parameter; and   generating a bitstream including the quantization values.   
     
     
         2 . The encoding method according to  claim 1 ,
 wherein the coefficient values are generated by a conversion process performed for each of a plurality of hierarchies.   
     
     
         3 . A decoding method for decoding items of attribute information that each correspond to a different one of a plurality of points, the decoding method to be executed by a decoding device including a processor and a memory, the decoding method comprising:
 obtaining quantization values from a bitstream;   calculating coefficient values by inversely quantizing the quantization values using a first parameter, the coefficient values being generated using a first parameter, using, for a coefficient value corresponding to a point located in a predetermined region among the plurality of points, a value assigned as the first parameter to the predetermined region, and using, for a coefficient value corresponding to a point not located in the predetermined region among the plurality of points, a predetermined value as the first parameter; and   calculating items of attribute information from the coefficient values.   
     
     
         4 . The decoding method according to  claim 3 ,
 wherein the items of attribute information are generated by a conversion process performed for each of a plurality of hierarchies.   
     
     
         5 . An encoding device comprising:
 a processor; and   a memory,   wherein using the memory, the processor:
 calculates coefficient values from items of attribute information, each of the items of attribute information corresponding to a different one of a plurality of points; 
 generates quantization values from the coefficient values using a first parameter, uses, for a coefficient value corresponding to a point located in a predetermined region among the plurality of points, a value assigned as the first parameter to the predetermined region, and uses, for a coefficient value corresponding to a point not located in the predetermined region among the plurality of points, a predetermined value as the first parameter; and 
 generates a bitstream including the quantization values. 
   
     
     
         6 . A decoding device that decodes items of attribute information that each correspond to a different one of a plurality of points, the decoding device comprising:
 a processor; and   a memory,   wherein using the memory, the processor:
 obtains quantization values from a bitstream; 
 calculates coefficient values by inversely quantizing the quantization values using a first parameter, the coefficient values being generated using a first parameter, uses, for a coefficient value corresponding to a point located in a predetermined region among the plurality of points, a value assigned as the first parameter to the predetermined region, and uses, for a coefficient value corresponding to a point not located in the predetermined region among the plurality of points, a predetermined value as the first parameter; and 
 calculates items of attribute information from the coefficient values.